The upcoming HBO Harry Potter TV series has added another major name to its cast. British actor Nicholas Hoult will play Gilderoy Lockhart in the show's second season, which will adapt Harry Potter and the Chamber of Secrets. The casting was confirmed by HBO Max.Hoult, 36, is known for films and shows including Mad Max: Fury Road, Superman, The Favourite, Nosferatu and The Great. He currently plays Lex Luthor in DC's Superman and is set to reprise the role in the upcoming sequel Man of Tomorrow.Who is Gilderoy Lockhart?Gilderoy Lockhart is one of the most memorable characters introduced in Harry Potter and the Chamber of Secrets. He becomes Hogwarts' Defence Against the Dark Arts professor and presents himself as a celebrated wizard and hero.However, Lockhart's public image hides a very different reality. He is a fraud who takes credit for the achievements of other witches and wizards by erasing their memories and claiming their heroic deeds as his own.In the 2002 film adaptation of Harry Potter and the Chamber of Secrets, the character was played by Kenneth Branagh. Hoult will now take over the role for the HBO series.When will the Harry Potter TV series premiere?The new Harry Potter series is scheduled to debut at Christmas 2026 on HBO and HBO Max. The first season will be titled Harry Potter and the Philosopher's Stone and will follow the first book in J.K. Rowling's series.The series is being developed as a new television adaptation of Rowling's seven-book series, with each season expected to focus on one book. Francesca Gardiner serves as writer and executive producer, while Mark Mylod is executive producer and will direct multiple episodes. Rowling, Neil Blair, Ruth Kenley-Letts and David Heyman are also executive producers.Harry Potter TV series full castThe central trio has been cast with newcomers Dominic McLaughlin as Harry Potter, Arabella Stanton as Hermione Granger and Alastair Stout as Ron Weasley.The main adult cast includes:John Lithgow as Albus DumbledoreJanet McTeer as Minerva McGonagallPaapa Essiedu as Severus SnapeNick Frost as Rubeus HagridLuke Thallon as Quirinus QuirrellPaul Whitehouse as Argus FilchWarwick Davis as Filius FlitwickAnton Lesser as Garrick OllivanderLouise Brealey as Madam Rolanda HoochBríd Brennan as Poppy PomfreyRichard Durden as Cuthbert BinnsSirine Saba as Pomona SproutLeigh Gill as GriphookThe Hogwarts students include Rory Wilmot as Neville Longbottom, Lox Pratt as Draco Malfoy, Leo Earley as Seamus Finnigan, Elijah Oshin as Dean Thomas, Tristan Harland as Fred Weasley, Gabriel Harland as George Weasley, Ruari Spooner as Percy Weasley, Alessia Leoni as Parvati Patil and Sienna Moosah as Lavender Brown.The Weasley family will feature Katherine Parkinson as Molly Weasley, while Johnny Flynn will play Lucius Malfoy. Daniel Rigby and Bel Powley have been cast as Vernon and Petunia Dursley, with Amos Kitson as Dudley Dursley. Bertie Carvel will portray Cornelius Fudge.The Slytherin students include William Nash as Gregory Goyle and Finn Stephens as Vincent Crabbe.Who will play Lord Voldemort?One of the biggest remaining questions surrounding the Harry Potter TV series is the casting of Lord Voldemort. The role has not yet been officially announced.Ralph Fiennes famously played Voldemort in the original film series and has previously suggested Tilda Swinton as a possible choice for the new adaptation.With Nicholas Hoult now joining the Season 2 cast as Gilderoy Lockhart, HBO's Harry Potter reboot continues to build its ensemble ahead of the show's Christmas 2026 debut.